this has also happend to me after i drunk a marijuana milkshake (cup full of mary jane smoke) and i was coughin like a bitch then i went and took a huge hit from a gigantic bong and i stood up to leave and all i could see was purple but i didnt fall tho. also my first time i used a gas mask it was full of smoke and stood up to get some soda im pretty sure breeble is right.